The present invention relates to a magnetic resonance imaging (MRI: Magnetic Resonance Imaging) apparatus. Particularly, the present invention is concerned with a magnetic resonance imaging apparatus of the type in which magnetic resonance signals are collected using plural receiving coils and multiple channels.
Imaging apparatuses, e.g., a magnetic resonance imaging apparatus, are known apparatuses for radiographing a slice image of a tomographic face of a subject and are used in various fields, including medical and industrial fields.
For example, when radiographing a slice image with use of a magnetic resonance imaging apparatus, first a subject is accommodated within a space with a static magnetic field formed therein and the direction of spin of protons present within the subject as a living body is regulated to the direction of the static magnetic field, affording a state of a magnetization vector having been obtained. Thereafter, an electromagnetic wave of a resonance frequency is radiated to the subject from an RF coil, thereby creating a nuclear magnetic resonance phenomenon and causing the magnetization vector of protons in the subject to be changed. Then, in the magnetic resonance imaging apparatus, magnetic resonance signals provided from protons of the subject returning to the original magnetization vector are received by probe coils (receiving coil units) and a slice image is produced on the basis of the received magnetic resonance signals (see, for example, Japanese Unexamined Patent Publication No. 2005-270304).
The magnetic resonance imaging apparatus, using probe coils (receiving coil units), receives magnetic resonance signals provided from a subject with an electromagnetic wave transmitted thereto. The probe coils have an inductance of a conductor and are configured to resonate at a predetermined frequency (see, for example, Japanese Unexamined Patent Publication No. 2000-225106).
In the magnetic resonance imaging apparatus, as probe coils which constitute receiving coil units there are known various shapes of such probe coils, e.g., a combination of plural coil bodies correspondingly to a subject to be radiographed. For example, the probe coils are connected to a data collector for collecting magnetic resonance signals provided from a subject with use of wiring such as coaxial cables.
The portion where the coaxial cables for the transmission of signals from the probe coils are connected to the data collector is constituted by a module board which is provided with plug sockets in a number corresponding to the number of probe coils. The signal provided from each probe coil and inputted to the associated plug socket installed in the module board, constitutes one channel.
The signals provided from the probe coils and inputted to the plug sockets installed in the module board are detected independently channel by channel in the data collector, then are digitized in a data processor and are reconstructed channel by channel, whereby an image is formed on a display of the magnetic resonance imaging apparatus.
Since coaxial cables are used for the transmission of signals from the probe coils to the data collector, there is a fear that there may occur a signal defect due to the inclusion of an electromagnetic noise, with consequent disturbance of an image displayed on a display of an operating unit.
For improving the radiographing speed of the magnetic resonance imaging apparatus there sometimes is adopted a parallel imaging method wherein signals provided from a subject are received in parallel by plural probe coils. For exhibiting the advantage of the parallel imaging method and attaining a high image equality it is considered necessary for the signal from each probe coil to have a high S/N performance.
Heretofore, however, there sometimes has occurred a case where the application of the parallel imaging method is difficult due to the inclusion of noise into coaxial cables, or it is impossible to fully cope with a lowering of S/N ratio which basically occurs with an increase of the radiographing speed. Thus, there also has occurred a problem such that the case to which the parallel imaging method is applicable is actually limited.
In case of collecting magnetic resonance signals through multiple channels in the application of the parallel imaging method, there is a fear of occurrence of crosstalk between signals being transmitted through coaxial cables of the channels. The larger the number of channels, the easier the occurrence of crosstalk. Even within the data collector there sometimes occurs crosstalk between signals in the channels.